Smith is best known for being the diet expert on “Celebrity Fit Club”; his book “The Fat Smash Diet” landed on the New York Times best-seller list. “The 4 Day Diet” emphasizes the importance of mental preparation in dieting. The program is broken down into four-day modules so you feel less overwhelmed.

This eight-week program is based on the idea that most diets don’t work because they go against people’s instinctive feelings to eat; Roberts offers ways to take control of those instincts so you still feel satisfied while losing weight.